Both a standard CT scan and a blood test known as CEA (carcinoembryonic antigen) improved doctors' chances of detecting and removing a recurrence of colon cancer, according to a study published in the Jan. 15 Journal of the American Medical Association.

Patients who received either of the tests were two to three times more likely to undergo another surgery that rid them of a recurring cancer, compared to colon cancer patients who did not receive follow-up screening after their initial surgery, found Dr. John Primrose, at the University of Southampton, and colleagues.

A U.S. expert said the findings suggest that the tests help spot cancer's return.

"They showed a higher level of detection of recurrence using CT or CEA than no surveillance, which reinforces the potential value of the test," said Dr. Durado Brooks, director of prostate and colorectal cancers for the American Cancer Society.

Both tests are relatively inexpensive and widely available in the United States, Brooks said. The CEA test is simple enough that it can be administered by a family doctor.

The CEA test looks for levels of a protein normally found in the tissue of a developing baby in the womb. If found in abnormal levels in adults, this protein is a sign of cancer, according to the U.S. National Library of Medicine.

"[The test] doesn't require a visit to a specialist or any kind of specialized training," Brooks said.

Colorectal cancer is the third most common cancer found among people in the United States, according to the American Cancer Society.

But the colon cancer death rate has been plummeting over the past two decades, due to improved forms of treatment and screening tools such as colonoscopy that can find and remove polyps before they become cancerous, according to the cancer society.

In the new study, researchers looked at whether these screening tools also could be used to keep patients healthy following colon cancer surgery.

More than 1,200 patients from 39 hospitals in England were split into one of four groups. The first group received minimal follow-up screening after surgery, the second received CT scans only, the third received CEA blood testing only and the fourth received both CEA testing and CT scans.

About 2.3 percent of the patients in the minimum follow-up group received a second surgery to cure them of recurring colon cancer. By comparison, 6.7 percent of the CEA group and 8 percent of the CT group received another surgery to treat a cancer recurrence.

People who received both CEA testing and a CT scan did not have any advantage in cancer detection, with 6.6 percent receiving additional surgery for recurring cancer.

However, this doesn't mean that the combined testing is without merit, Brooks said. Some of those patients had a CEA test that was normal but a CT scan that detected cancer, he said.

"Now the question is whether there are some higher-risk subsections of patients who would benefit from that combined approach," Brooks said. "It appears there are some instances where it works better."

Another expert said this is an important study that could change how doctors follow colon cancer patients after surgery.

Doctors could start favoring the CEA test for post-surgery screening, since it is much cheaper than CT scans and doesn't expose patients to radiation, said Dr. David Bernstein, chief of the division of hepatology at North Shore University Hospital in Manhasset, N.Y.

In addition, he said, the lack of added benefit by combining the two might put an end to a combined approach in tracking most colon cancer patients.

"It should lead them away from using the two together," Bernstein said. "It doesn't save lives, but it does cost a lot more."

The study also contains a piece of good news for colon cancer patients. More than two-thirds of patients who underwent surgery to cure their cancer were still alive an average of four years later, "suggesting that five-year survival may be more than the 40 percent previously reported," the researchers wrote.

Because of this, the researchers were unable to show that the follow-up testing had any effect on survival rates.

"The overall five-year survival after surgery for colorectal cancer was actually quite good," Brooks said. "The reality is, many people survive for very long periods of time, and many people survive cancer-free. Because the survival of the entire group of people is already pretty good, you may need another three to five years to determine how much survival is impacted by testing."